Skelet 1

Unsolved problem:

What is the cycle start time of Skelet 1? The best known lower bound is $10^{24}$.

1RB1RD_1LC0RC_1RA1LD_0RE0LB_---1RC (bbch)

A skeleton warrior holding a sword. The runic inscription on its blade is a string that is particularly often encountered on a tape during Skelet 1 simulation.

One of the most challenging BB(5) Turing machines to prove non-halting. It was eventually proven to be a Translated Cycler with period 8,468,569,863 and start step about $5.42\times 10^{51}$

Preperiod

The exact preperiod (minimum cycle start start step) for Skelet 1 is not known, but @hipparcos computed it to be approximately 5418883027667422764169643414989497193809945789706483. This is an upper bound (by this point the TM is cycling). This value is probably accurate to within about one period.

See Also

• https://www.sligocki.com/2023/02/25/skelet-1-wip.html
• https://www.sligocki.com/2023/02/27/skelet-1-halting-config.html
• https://www.sligocki.com/2023/03/13/skelet-1-infinite.html